I recently put a new FICM on my truck. I have the 4 in. dual exhaust ( no cat or muffler) so you can reallly hear the turbo hiss. I dont remeber this happening before replacing the FICM but now I hear the turbo disengaing through the exhaust at a idol. Theres a strong hiss then nothing for about 20 -30 sec and then the hiss again for 2-3 min and then nothing.. When I bought the FICM I just put it on the truck and it started, so I have not gotten it flashed since. Is this normal? or should I get prepared for a problem.
Turbo Question
- Thread starter lomac9
- Start date
DaveBen
SDD Senior Member
Most turbos whine with a high pitched sound and do not hiss. The hiss maybe an air leak somewhere. I am not sure how the FICM (Fuel Injection Control Module) would play into all of this. 
Dave
Dave
ok its a hissing whine noise. Im not sure if the FICM would cause anything or not. Maybe its just coincedental but I do not remeber my turbo sounding like it has disengaged before. The exhaust is obviously louder due to no muff or cat. When I start it theres a hiss (whine) noise for about 2-3 at idle then th enoise goes away ( LIke the turbo has disengaged, or whatver someone wants to call it) for about 20 secs then the whine (hiss comes back. Im trying to describe it the best I can. Its almost like theres exhaust coming out the back 2-3 mins and then there is none for 20-30 secs then exhaust so on and so on. I only hear this at a idle. Truck runs perfectly . This might be nornmal I just dont remeber it doing it before the FICM
DaveBen
SDD Senior Member
The turbo never becomes disengaged. It is always spinning, but not necessarily making boost.
Dave
Dave
ok when im hearing the noise when i start it its making some boost and thats when i hear threw the exhaust. When it stops boost the noise pretty much stops. Thanks I appreciate that. Didnt think the turbo actually disengaged just didnt know the terminology to use. Thanks again
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DaveBen
SDD Senior Member
No Problem Iomac9. We all have to get up to speed on these motors and terminology. You will soon catch on. 
Dave
Dave
